沼 is a Japanese kanji written with 8 strokes, listed here under the keyword “marsh”. It is built from 召 (seduce) and 水 (water). In Remembering the Kanji by James W. Heisig it is frame 145.
On KumiJi Glyph Explorer, open the parts search and type “seduce” + “water”. 沼 is among the results, together with every other character containing the same shapes.
Open 沼 in the interactive kanji search
to expand every part down to its smallest pieces, add your own names and mnemonic stories,
or search for other characters by their parts.